9. PROJECT SUMMARY/ABSTRACT Most modern day cochlear implant (CI) candidates have residual acoustic hearing in one or both ears. Several studies have shown that this residual hearing provides significant benefit when paired with a CI in a bimodal listening configuration. The degree of acoustic-related, bimodal benefit however, varies across ears and is not correlated with audiometric threshold, etiology, age or preoperative speech recognition. In the absence of gross differences in preoperative hearing acuity, patients presenting with residual hearing in both ears are commonly told that either ear could provide benefit when paired with a CI. There is no clinical measure that provides predictive utility for selecting the ear to be implanted-a critical consideration particularly in cases for which bilateral cochlear implantation may be restricted (i.e. insurance restrictions such as encountered with Medicare and Medicaid). This application proposes to develop and implement such a clinical tool. The clinical test of spectral modulation detection (SMD) is a modified version of a validated psychophysical procedure assessing spectral resolution. In this task, the listener is asked to discriminate spectrally-flat noise from spectrally-modulated noise. Pilot work on this clinical procedure has shown SMD in the non-implanted ear is an excellent predictor of acoustic benefit (r = 0.89) when paired with a CI for bimodal hearing. Because this task contrasts noise stimuli, it does not require speech understanding and can be completed by candidates with very little residual hearing-both of which are expected for individuals being evaluated preoperatively. Pilot work with our most recent iteration of the clinical task takes 5 to 6 minutes per ear, is highly correlated with acoustic benefit in quiet and noise, and is reported as a percent correct score. This tool has the potential to satisfy a strong need in the fields of audiology and otology as well as significantly influence surgical decisions and patient outcomes. At the conclusion of this study, we will provide clinicians with a pre- and post-implant test of auditory integrity, the supporting tools to translate test scores to meaningful predictions about the potential benefit of each ear in specific treatment conditions, and a data-driven guide to ear selection. Thus, the study has the potential to help us meet the evidence-based objective in medicine in the areas of implant ear selection, expectations management, and modality selection (bimodal hearing or bilateral implantation).